1. The Field of the Invention
The present invention relates to optical connectors, and more particularly to ferrule-type plug/receptacle optical connectors.
2. The Relevant Technology
Ferrule-type plug/receptacle optical connectors are well known in the art. These connectors are typically used to position two optical waveguides, such as optical fibers, so that light can propagate between the two waveguides or between the optical waveguide and an optical component or subassembly. The optical connectors can be repeatedly removed and reconnected to each other while providing an optical alignment therebetween to minimize connection losses.
A common ferrule-type optical connector, designated generally as reference numeral 100, is illustrated in FIGS. 1A and 1B. As shown in FIG. 1B, connector 100 includes a base 102 that receives a ferrule 104. The base 102 includes a central bore 106 that extends from a first end 108 toward a second end 124 having an annular alignment recess 109 formed therein. The recess 109 is centered about bore 106. The recess 109 includes a bottom wall 112 and a sidewall 114. A post member 110 extends from bottom wall 112 and towards a center of recess 109, with bore 106 running through post member 110. The sidewall 114 of recess 109 has a height above bottom wall 112 that is greater than that of post member 110. A retention channel 116 is formed in a lateral outer surface of base 102 that acts as the mating structure to receive a portion of the housing/shell (not shown) of the transceiver module that contains the receiver optical sub-assembly (ROSA) and transmitter optical sub-assembly (TOSA) (not shown).
The ferrule 104 received by base 102 has a generally cylindrical shape, with an annular outer sidewall 118 and a mating surface 120 on an end 126. A central bore 122 runs through ferrule 104. The ferrule 104 inserts into recess 109 of base 102 until ferrule mating surface 120 engages with recess bottom surface 112, as is shown in FIG. 1A. The outer diameter of ferrule sidewall 118 is slightly larger than an inner diameter of recess sidewall 114, so that there is an interference fit therebetween. This interference fit ensures that ferrule 104 is correctly positioned both laterally and axially when mating surface 120 engages bottom surface 112. The combination of the mating surfaces and the interference fit between base 102 and ferrule 104 ensures that the bores 106/122 (and therefore optical elements and waveguides disposed therein) are precisely aligned with each other.
One problem that has been discovered is that many times the lateral forces of the interference fit between base 102 and ferrule 104 causes deformation of ferrule 104. This deformation results in bore 122 actually curving inwardly opposite the contact area between sidewall surfaces 114/118. This curvature can interfere with the waveguide and/or other optical components mounted in bore 122. It can also prevent these components from being properly positioned relative to bore 106 of base 102 and any optical elements therein.
One solution can be to reduce the lateral forces of, or completely eliminate, the interference fit between ferrule 104 and base 102. However, any free space between sidewall surfaces 114/118 allows lateral movement between base 102 and ferrule 104 that misaligns bores 106/122. This can cause misalignment of the optical components with associated degradation of alignment and optical coupling.